**Retro Review: Texas Instruments TI-57 LCD**

**Quick Facts:**

Model: TI-57 LCD

Company: Texas Instruments

Years: 1982-1984

Type: Programming

Batteries: 2 x LR44

Operating Mode: AOS

Memory Registers: Minimum of 1, Maximum of 8

Program Steps: Minimum of 0, Maximum of 48

Similar to many Texas Instruments programming calculators of the 1970s and 1980s, the memory can be partition between memory steps and program steps by the [ 2nd ] [ Part ] key sequence. Each register has 8 program steps.

Some Partitions:

Part 1: 1 register (R0), 48 steps

Part 2: 2 registers (R0, R1), 40 steps

Part 3: 3 registers (R0, R1, R2), 32 steps

Part 4: 4 registers (R0, R1, R2, R3), 24 steps

**Features**

* trigonometric functions and inverses

* polar/rectangular conversions and degrees/degrees-minutes-seconds conversions

* integer part (Intg), fractional part (Frac), absolute value ( |x| )

* logarithms (log, ln x)

* storage arithmetic ([STO] followed by +, -, ×, ÷, y^x, INV y^x)

INV Key combinations

[ INV ] [ sin ]: arcsin

[ INV ] [ cos ]: arccos

[ INV ] [ tan ]: arctan

[ 2nd ] [ INV ] (P<>R): rectangular to polar

[ 2nd ] [ INV ] (DMS-DD): degrees to degrees-minutes-seconds

[ INV ] [ y^x ]: y^(1/x)

[ INV ] [ log ]: 10^x

[ INV ] [ ln ]: e^x

[ 2nd ] [ INV ] (SBR): RETURN - this ends subroutines

[ 2nd ] [ INV ] (Dsz): Decrement R0 by 1 and skip if R0 ≠ 0

Polar to Rectangular:

r [ x<>t ] θ [ 2nd ] [ P<>R ]: y [ x<>t ] x

Rectangular to Polar:

x [ x<>t ] y [ 2nd ] [ INV ] [ P<>R ]: θ [ x<>t ] r

**Keystroke Programming**

The TI-57 LCD is a keystroke programmable calculator. However, programming steps are at a premium with a maximum of 48 steps (allowing for one memory register) to 0 (yes, zero) if you use all 8 registers (R0 to R7).

Programming commands include:

* Test with the t register: x=t, x≥t, and inverses

* Decrement and Skip: either skip on zero or not on zero. This command works on register 0.

* Labels and Go to commands: labels 0-9

* Pause command

* Subroutines (SBR)

* Go to step zero (RST)

Thankfully some steps are merged, mainly with the [ INV ] key, [ GTO ] key (GO TO command), [ 2nd ] key, and storage arithmetic.

What is interesting is that there are no statistical functions on the TI-57 LCD. See the One Variable Statistics section for a 25-step program to add one-variable statistics.

**Keyboard**

We need to talk about the keyboard. The keyboard looks good. I have the United States edition of the TI-57 LCD and I like the blue, gray, black, and white color scheme.

Unfortunately, some keys are hard to press and other keys can produce a double-stroke. With the calculator I got, one wrong press gives a double number (22 instead of 2, 00 instead of 0) while some keys pressed in the "wrong" way do not register. This does not allow for fast typing. I think I found the keys "sweet spots": the right side of the keys.

The keyboard difficulties are a common complaint with the TI-57 LCD. They are corrected with the TI-57 II released in 1986.

**TI-57 LCD Program: One Variable Statistics**

Memory Registers Required: 3 (Part 3)

00 23.01 LBL 1 // data entry

01 61.85.01 STO+ 1

02 34 x^2

03 61.85.02 STO+ 2

04 1 1

05 61.85.00 STO+ 0

06 13 R/S

07 22.01 GTO 1

08 23.02 LBL 2 // calculation

09 71.01 RCL 1

10 55 ÷

11 71.00 RCL 0

12 95 =

13 13 R/S // sample mean

14 71.02 RCL 2

15 55 ÷

16 71.00 RCL 0

17 75 -

18 53 (

19 71.01 RCL 1

20 55 ÷

21 71.00 RCL 0

22 54 )

23 34 x^2

24 95 =

25 35 √

26 13 R/S // population deviation

Registers used:

R0 = number of data points = n

R1 = sum of the data points = Σx

R2 = sum of the data points squared = Σx^2

Mean:

x-bar = Σx / n

Population Deviation

σx = √( Σx^2/n - (Σx/n)^2 )

Instructions:

1. If necessary, partition memory to fit 3 memory registers (R0, R1, R2). [ 2nd ] (Part) [ 3 ].

2. Enter the first point, press [ GTO ] [ 1 ], then [ R/S ]. 1 is displayed when data points are entered.

3. Enter each subsequent point, press [ R/S ]. Repeat until finished.

4. To calculate the mean and population deviation, press [ GTO ] [ 2 ]. The mean is displayed first, press [ R/S ] to display population deviation.

[ RCL ] [ 0 ]: number of points

[ RCL ] [ 1 ]: sum of data points

[ RCL ] [ 2 ]: sum of squares of data points

Example 1:

Data Set: 4, 5, 9, 8, 6

Results:

n = 5

Σx = 32

Σx^2 = 222

x-bar = 6.4

σx = 1.854723699

Example 2:

Data Set: 11058, 12360, 12445, 12761, 13002, 13360

Results:

n = 6

Σx = 74986

Σx^2 ≈ 9.40 * 10^8

x-bar = 12497.66667

σx = 725.9110757

**Closing Thoughts**

I wish the TI-57 LCD had both more memory and functions. Honestly, Texas Instruments could combine the functions of the TI-57 LCD (tests, labels, go to, decrement and skip), the TI-55 III (better keyboard, linear regression, integrals, unit conversions, signum function, permutations, combinations), and the later TI-60 (the TI-55III with base conversions) with a total of 188 steps. The programming set up with the TI-57 LCD wins with it's merged steps with INV, STO, LBL, and GTO.

Overall, I like the appearance of the TI-57 LCD, despite the keyboard's set backs. That, the lack of functions and statistics, and the sometimes slow execution and we can see why the TI-57 LCD was not a best seller.

**HP 32S and HP 32SII Week: May 2, 2022 - May 6, 2022**

Until next time,

Eddie

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